Field of the Invention
This invention relates to systems for controlling the flow of gas in pipelines and more particularly, to an exhaust reduction system for controlling devices, which system is designed to reduce the exhaust control gas emissions from the controlling devices in the course of controlling the flow of gas by means of control valves through a pipeline. In a preferred embodiment, the exhaust reduction system of this invention is coupled to a conventional pipeline pressure regulator for receiving a flow of control gas and reducing the gas pressure to a desired system pressure. This control gas stream is introduced into a system high pressure regulator and a system low pressure regulator, where the pressure is further sequentially reduced and adjusted by manipulating adjusting knobs in the system high pressure regulator and system low pressure regulator. The gas stream is then exhausted from the low pressure regulator to at least one gas controlling device such as a back pressure controller, downstream controller and flow controller, where it is exhausted at various pressures, depending upon the number and characteristics of the controllers used. One or more gas streams from the controller or controllers are then introduced directly into one chamber of a gas pressure multiplier (in the case of a single controller) or into separate ports of a high or low discriminating pressure selector relay (in the case of two or more controllers) and, in the latter case, the gas stream having the highest or lowest pressure is exhausted from the selector relay and introduced into one chamber of the gas pressure multiplier. The gas pressure multiplier then increases or multiplies the gas pressure in a second chamber of the gas pressure multiplier in a selected ratio, typically 1 to 3 or 1 to 6 and exhausts the gas at a desired low multiplied pressure, directly to the control valve mechanism of the control valve which operates to regulate the flow of gas through the pipeline.
Accordingly, in a preferred embodiment of the invention gas from the conventional line pressure regulator can be introduced into the system high pressure regulator and the system low pressure regulator as described above and from the system low pressure regulator at a regulated pressure, directly to either a back pressure controller, downstream controller or a flow controller, from which the gas stream is introduced directly into a first chamber of the multiplier and from the second multiplier chamber, into the control valve, as described above.
In another preferred embodiment of the invention the control gas flow from the line pressure regulator can be introduced into the system high pressure regulator and the system low pressure regulator as described above and from the system low pressure regulator at a selected pressure into any two of the three back pressure controller, downstream controller and flow controller and from these flow controllers into a selector relay controller. From the selector relay controller the control gas is routed into a first chamber of the gas pressure multiplier, where the gas stream in a second chamber is multiplied in a selected ratio, typically of from 1 to 3 or 1 to 6, and is subsequently introduced at a selected low pressure into the control valve.
One of the problems inherent in conventional gas systems for operating pipeline control valves is that of excessive exhausting of the controlling device gas itself, typically natural gas, into the atmosphere during the process of operating the pipeline control valves. This excessive use of control valve gas is apparent due to the relatively high control gas pressure (about 20 psi) which is normally used to operate the control valves. For example, the Fisher 4160 control valve system exhausts from about 48 to about 309 mcf per year natural gas into the atmosphere. If natural gas is assumed to have a value for comparison purposes of $2.50 per mcf, the monetary loss range is from $120.00 to $772.50 for each control valve which is served by a Fisher 4160 control device. In contrast, the exhaust reduction system of this invention has been found to exhaust from about 23 to about 106 mcf per year, for a minimal annual saving in gas loss of $62.50 and a maximum gas saving loss of $498.00. Accordingly, the exhaust reduction system of this invention saves from 52% to 63% of the control gas which would be otherwise lost in operating a typical control valve in natural gas pipeline control systems.
Accordingly, it is an object of this invention to provide a new and improved exhaust reduction system for controlling devices that operate control valves, which system minimizes the volume of gas exhausted from the controlling devices during operation of the control valves.
Another object of this invention is to provide an exhaust reduction system for operating controlling devices in natural gas and other gas systems, which system is designed to control the pressure of a control stream of gas to the control valve and minimize the volume of gas exhausted into the atmosphere from the control valves during operation of the control valves.
A still further object of this invention is to provide a natural gas exhaust reduction system for controlling control valves mounted on pipelines and regulating the flow of natural gas through the pipelines, which system is used in association with a conventional pressure regulator that reduces the pressure of a control stream of gas diverted from the pipeline, to a selected entry pressure. The system includes an adjustable high pressure regulator and an adjustable low pressure regulator for further reducing the pressure of the control gas stream from the pressure regulator and introducing the gas at a much reduced and regulated pressure to a gas controller. The gas is channeled from the controller to a first chamber of a gas pressure multiplier and a separate volume of gas is supplied from a second chamber of the gas pressure multiplier at a selected, multiplied, yet low, operating control pressure, into the control valve.
Yet another object of the invention is to provide an exhaust reduction system for controlling control valves which regulate the flow of natural gas or other gas through pipelines, which system is linked to a conventional pressure regulator that reduces the pressure of a control gas stream from the pipeline into a system housing containing a system high pressure regulator, a system low pressure regulator, a selector relay and a gas pressure multiplier. The gas is routed first from the conventional pressure regulator through the system high pressure regulator, where the pressure is reduced by manipulating an adjusting knob to a selected value, after which, it is introduced into the system low pressure regulator for further reduction, in like manner. The control gas is then exhausted from the system low pressure regulator into a back pressure controller, a downstream controller and a flow controller at a constant pressure and is exhausted from these controllers at varying pressures, into the respective ports of the selector relay. The highest gas pressure stream entering the selector relay is allowed to flow from the selector relay and is introduced into a first chamber of the gas pressure multiplier, which multiplies gas in a second multiplier chamber in a selected ratio, typically in the range of from 1:3 to 1:6. The gas in the second chamber is subsequently introduced into the control components of the control valve.